Comment 9 for bug 633681

BTW, not only filters, but also any package that
disables the internal dependency generator, starts
to use getOutputFrom(). So the problem likely
tracks with a disabled internal dependency generator.

The othe usage case is with %doc copying, but there's
no data transferred on the helper pipe.

DIsabling the internal dependency generator and setting
one of the %_find_provides/%_find_requires extractors
to /bin/true in some package with a modestly
large (more than 8Kb perhaps much more) file list should
give you an easier reproducer than random failures in a remote
build system.

And replacing /bin/true with a short script that reads
everything from stdin before exiting will indicate the
nature of the fix.